Affiliation:
1. Laboratory of Mineralization and Dynamics, College of Earth Sciences and Land Resources Chang'an University 126 Yanta Road, Xi'an 710054 China
2. Laboratory for Inorganic Chemistry ETH Zürich Vladimir Prelog Weg 1, CH‐8093 Zürich Switzerland
Abstract
Lithium isotope measurement in spodumene by femtosecond LA‐MC‐ICP‐MS was investigated and the influence of plasma operating conditions and data reduction strategy on accuracy and precision was studied. It was found that “hot” plasma conditions led to an unstable baseline signal and substantial variations in the Li isotope ratios. By adding a constant amount of water to the carrier gas, a stable baseline was achieved and isotope ratios became reproducible and were consistent with data from solution‐based MC‐ICP‐MS. The resulting biases were within ± 0.51‰ and the reproducibility was better than 0.09‰. Comparison of Li isotope ratios resulting from different data evaluation schemes showed that the mean of the transient intensity ratios, integration of the entire or a user‐defined period of the ion signals resulted in good agreement with solution‐based data, while linear regression underestimated the Li isotope ratios. It was also found that “cool” plasma operation produced a stable baseline signal, but the Li isotope results were biased by up to ‐4.3%, irrespective of water introduction and the data evaluation scheme. With the optimised “hot‐wet” conditions, the Li isotope ratios in eleven spodumene materials were determined which successfully allowed distinguishing regional deposits and partially veins of the available samples.
Funder
China Scholarship Council
Eidgenössische Technische Hochschule Zürich
Natural Science Foundation of Shaanxi Province
Subject
Geochemistry and Petrology,Geology,Geochemistry and Petrology,Geology